Energy – Something for Nothing……

22 Jun

‘Our insatiable need for energy continues to grow exponentially.  Burning fossil fuels is still the predominant source, alongside the minor contribution from ‘renewables’ but I believe we are missing out on an opportunity to get something for nothing……’


Something for Nothing……

The laws of thermodynamics state that energy cannot be created or destroyed; only changed from form to another, so the title of this post is somewhat misleading but read on and all will become clear……

The Stirling Cycle……

The Stirling engine was patented in 1816 by Robert Stirling and is virtually unheard of outside of academic circles.  It differs from all other types of engine in one simple respect.  Whereas most engines take in fuel from an external source, convert it to create a mechanical force and then expel or exhaust the spent fuel, the Stirling cycle is sealed.  It exploits a temperature differential to create mechanical work.  See the diagram below which shows a basic Stirling cycle.

The Stirling Cycle

The Stirling Cycle

There are many different designs of Stirling engine from the single cylinder example above, to more complicated designs employing more than one cylinder and the use of more efficient heat exchangers but all work on the same principal……

Click on this link to see an animation of the cycle:

Applications and Possibilities……

Many larger scale applications using the Stirling cycle have been tried with some success.  NASA and the Ford Motor Company have both attempted to build vehicles which were exclusively powered by Stirling engines.  The main problem with such uses is the slow response to sudden demands for power.  However, the use of Stirling engines to generate electrical power using existing technologies has been more successful.

My own interest in the use of the Stirling cycle is on a more local scale.  The Stirling cycle works in both directions; that is the temperature differential can be high to low, or low to high.  When one thinks of the number of situations where heat is expelled either intentionally, as in refrigeration, or unintentionally as part of a normal domestic heating system, small scale Stirling engines could be used to provide electricity.  Hermetically sealed systems using gases such as Hydrogen easily outperform Photo-Voltaic Cells.


There are many ways in and around your home where a temperature differential exists and which could ‘fuel’ a Stirling cycle.  It is certainly not the answer to the planets energy needs but given enough small scale operations could contribute toward a reduction in our need for fossil fuels.  Put on your thinking caps and see if you could find ways to benefit from what would otherwise be wasted energy……



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